1. Field of the Invention
This invention relates to wheelchairs, and more particularly to a wheelchair which can elevate its occupant from a sitting position to any position up to a normal standing position, at which positions the wheelchair can be move about to enable the occupant to perform useful work. The wheelchair can also move its occupant from a sitting position to a reclining position to facilitate the transfer of the individual from the wheelchair to a bed.
2. Summary of Related Art
Wheelchair design have become quite sophisticated as a result of efforts intended to enable handicapped individuals to have a degree of control over their own movements. In order to help handicapped individuals return to a normal working environment, they must be able to simulate normal mobility and positioning. Thus, powered wheelchairs have incorporated a wide variety of control and safety devices to assist handicapped operators of wheelchairs in achieving relatively independent movement and transportation.
Wheelchairs have been previously developed which are able to manipulate the handicapped person into the upright position. The ability to achieve a standing position provides many medical benefits as well as increased independence and morale. Wheelchairs have been designed to permit the handicapped person to position himself to work at a number of work stations and to remain in a standing position for several hours at a time. Such wheelchairs are deficient for a variety of reasons.
Stability and mobility are the two primary problems in stand-up wheelchairs. Prior art devices were unstable because most of the weight would be placed on the front of the wheelchair when the handicapped person was in the standing position. In the standing position, the user's body typically extends substantially forward and above the center of gravity of the wheelchair, which may cause the individual to fall forward when attempting to stand.
The present devices for achieving proper weight distribution to stabilize the wheelchair are not satisfying the demands of the users. Selective positioning of the individual is difficult and the large size of the wheelchair needed to achieve proper weight distribution is a serious drawback. In addition to the body weight of the handicapped individual, the weight of the batteries used to power the wheelchair weigh up to 100 pounds, which complicates the weight distribution dynamics in changing from a seated or reclined position to a standing position.
Large wheelchairs typically sacrifice mobility and maneuverability in order to overcome the stability problem. Large wheelchairs are difficult to maneuver in close quarters. Since space is often at a premium in both an office and manufacturing location, it is desirable to have a wheelchair that is highly maneuverable. In addition, many stand-up wheelchairs are not ambulatory when the user is in a standing position.
The stand-up wheelchair must also provide sufficient support to the standing user. Handicapped individuals typically have no leg control or use whatsoever. The stand-up wheelchair must support the user's body during the standing process. Achieving the proper support without effecting mobility is generally difficult to accomplish.
A number of stand-up wheel chairs have been developed to provide handicapped individuals with wheelchairs having stand-up capabilities. U.S. Pat. No. 4,054,319 to Fogg, Jr. et al describes a stand-aid wheelchair for supporting handicapped individuals in a standing position. The wheelchair includes an extended chassis with poor maneuverability.
U.S. Pat. Nos. 4,390,076 and 4,456,086 to Wier et al disclose an integrated ambulator and wheelchair to enable a handicapped individual to stand on the ambulator and be separated from the wheelchair for maneuvering in confined spaces. This invention includes a separable walker and a power platform for standing and maneuverability purposes.
U.S. Pat. No. 4,437,537 to Ausmus teaches a stand up motor driven vehicle for use by handicapped individual. The apparatus tilts forward to for retrieving articles. The apparatus does not includes any seating or reclining position.
U.S. Pat. No. 4,809,804 to Houston et al. discloses a combination wheelchair and walker apparatus which moves a handicapped individual between a seated position and an upright position. The apparatus does not have a reclining position.
U.S. Pat. No. 4,948,156 to Fortner shows a standing support apparatus which can be attached to a wheelchair. The individual using the standing support must have sufficient strength to pull himself into an upright position.
U.S. Pat. No. 5,096,008 to Mankowski discloses a wheelchair which includes a main drive for positioning the wheelchair. The seat is rotatable ninety degrees and includes an adjustable foot plate. The handicapped individual can stand at approximately floor level and work at his normal height when supported by the apparatus.